I designed a 3D model of a .30 Caliber pellet - A Tester Needed

[Triglav]

7,62 / .30 caliber hits hard I heard...

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Hello there everyone!



I'm new here folks, just joined a couple of hours ago... I go by the name of Triglav and I'm just an average Joe, no-one special and an airgun enthusiast.

I own a few of these things, 3 air rifles chambered in .177 and one in .22 - that one being the Gamo Black Bear in 5,5 mm.



Now, there's an air rifle, that's been in my sights, or well on my wishlist for quite a while now - the one and only Hatsan model 130S, chambered in .30 caliber (7,62 mm).

The thing is, before I make the final decision to go and get this thing from an airgun store on the other side of my country, I'd like to know, how this thing would perform with 
rather lightweight ammunition for a .30 cal, such would be these 3D printed pellet bodies with .22 Slugs or BBs stuck into the hollows of their head. I reckon they'll fly

really fast due to their lighter weight; The standard .30 caliber pellet from JSB weighs 2,9 grams / 44.75 grains and flies at 550 FPS on average and I'm sure that these pellets,

that I've designed would fly much faster.

I'm giving away free 3D models here, of these .30 caliber pellets, that I've designed and which can of course be 3D printed from either PLA (the cheapest material), 
ABS (probably not the best option out there) or even Nylon or anything else in between. I've personally never handled a 3D printer before - I'm planning on getting one

someday, but right now I don't really have a serious need for one and with this said I'd like someone to 3D print a couple of these and test them. I've also designed other

3D models for printing in the past, everything from suppressor baffles to mounting systems for optics and even chassis for AR styled stocks and so far all of these designs/

3D models of mine have been printed properly by my friends to whom I've given them, true to their model dimensions.



If anyone here has got the time and will to print a couple of these pellets and test them through their .30 cal airguns (preferably through the Hatsan 130S/ 135 - .30) for both

accuracy and velocity, I would appreciate it a lot! Oh, and don't forget to weight them too.



So, all you're going to have to do is to print them, well obviously... and then you'll have to either shove or glue a .22 cal BB or a JSB Knockout SLUG into the place of their

heads and that will be it (Check the image, that I've attached to this post). While I was making these models I had assumed, that without the BBs or Slugs, the pellets would

simply be too light and without a proper balancing point, so I've thought of BB/Slug tips. BTW, the pellet with the BB is roughly 10 mm tall without the BB and the other,

classic dome shaped pellet with a JSB KO Slug in its head is 12 milimeters tall. Same goes for the hybrid slug body of the red pellet - check the attached image (I just assigned

a red colour to it, when it's going to get printed it'll be of the filament's colour).

View attachment 3D_Pellets_762.1624502336.zip




Once again, I'd be delighted to see how these'll perform and of course I'd also like to give a big thanks to all of you folks reading this.

The files and images are in the zip file.



- Triglav

 

[Motorhead]

Weight distribution is KEY to stability and that changes with speed shot, barrels twist rate and OAL of the pellet.



Good luck !!

 

[Triglav]

I reckon "OAL" stands for overall length?

Also yes, you are very much correct about twist rates, my break-barrels all shoot decently with "Hybrid slugs", such as the Crosman's Powershot Penetrators or ELKO Red Magnums or even with Norica Prometheus pellets to a lesser extent in .22 of course (Tested through my Gamo Black Bear).

 

[UCChris]

My concern is that the shot cycle of a springer gets real ugly when you use ammo that is too light. The experiment is quite interesting from a PCP perspective, since I'd be worried about the 3d print fragmenting and then you're basically dry firing your springer. 

 

[Motorhead]

I reckon "OAL" stands for overall length?

Bear).

Correct

 

[DanWho]

I'm willing to give it a try, but I will probably have a big problem with overspeed. I have a RAW .30 but when I get it out to the range I will see what I can do with it, I have not had the chance to even fit a scope or fire even a single round out of it yet. Last sunday I wanted to go to the range but we had thunderstorms and acording to the forecast it isn't looking for this Sunday either (dang nab it ). But if it manages to stay clear I will try running a few out of it and let you know what I find out.

Could I suggest more of a break open sabot, once it leaves the barrel the sides split open and it falls away leaving the slug to travel by its self. might have to single load to do this right, but I would be willing to play with several designs if you have them

Dan

 

[Triglav]

Thank you so much! 

By the way, take your time with it, it ain't a race  

I think that for a .30 such as yours, a print out of nylon should work the best, because nylon is really hard; So hard in fact, that it can withstand a detonation of a .22 LR within it, if the barrel of a 3D printed gun, such as the Songbird 22LR, is made out of it - for all I know that gun still shoots even after 60+ rounds of CCI minimags have been fired through its barrel.

Check these two videos out, they might give you a clue on what might happen:

- https://www.youtube.com/watch?v=AlIDQCgZoUc

- https://www.youtube.com/watch?v=ETYN4lJyk58

I'll start working on the sabots in the evening, I'll have them ready in a couple of days. I already have an idea, that'll probably work best.



... and of course, thank you once again.

Later.

 

[DanWho]

Nylon is not something I have ever used, I have pla, tpu and petg. I tried printing out 6x6 last night but had a problem with some of them. I'm going to have to do a little more fine tuning. I printed with a layer height of .12 mm I will give it an other try tonight when I get home tonight.

 

[Triglav]

PLA it is then, it's pretty solid and hard enough I think. Now, about the prints; You mentioned that you ran into some problems while printing the pellets... Did all of them give you trouble or just some? Are the dimensions perhaps off?

Because they really shouldn't be, I checked whether everything checks out on the models in terms of the pellets' diameters and it really does; the head is 7,62 mm exactly, while the skirt is a little wider, at about 8,04 mm and the heights range from 10 -12 millimeters, depending on the pellet type - BB tipped, Hybrid Slug...

BTW, did you use supports when printing? Because supports could cause issues for all I know. As you've said, give it another try and that'll be it.



Thanks again for doing this!

 

[DanWho]

No it wasnt the models, I think my bed is a little wavey if it is, its not by a large ammount. Of the 6x6 print I lost the 3 on the left and because of loosing the 3 on the left I ended up with strings haning off the others.which would make them fly wierd because they wouldnt be that smooth.

I got home and fell asleep, but I will play with the printer so I have something to go to the range with and give you some feedback.

Im not so sure about PLA, it may have some trouble conforming to the polygon barrel, Ill give it a shot with PLA first. The PETG might be a better choice because of the shape of the barrel. TPU would be like running an eraser down the barrel, it would seal too good. One way or another I will test the PLA tomorrow if the weather cooperates and will try PETG in a week or two again depending on weather. Some how Ill get some testing done even if means doing some back yard testing with a short range. The best I can do in my back yard is about 40 yards and easier to work with 30-35 yards. But because Im within city limits I cant imagine anyone near me happy if end up going supersonic.

 

[Triglav]

Oh, thank god I didn't screw up the measurements on the models, I'd never forgive myself for that! 

Too bad you lost your print because of those 3 on the left, but I'm sure you're going to be able to get it right next time somehow. However, how come you think, that PETG works better with polygonal barrels? I know that polygonal barrels seal the gases better than standard/round ones, because the bullet is round and the bore pentagonal/hexagonal, which means, that the round bullet fits and basically deforms around its edges to the hex/pen shape of the barrel; So wouldn't PETG have a harder time deforming due to its higher physical strength and better heat resistance than PLA? I'm just being curios at this point...

But as I've said, take your time with these things and shooting at 30-35 yards range will certainly tell you, whether these will fly well or not. Also, try not getting into trouble with the law by going supersonic

Till' next time 

 

[DanWho]

PLA is a harder plastic that doesn't deform too well under quick stress, where as PETG will deform better because its a softer more pliable plastic.

I sliced and printed the holder with everything the same except slicing tollerance, I printed them with interior, exterior and middle. Layer hight was .12mm with the line width of the .4mm nozzle set to .46mm. I ended up with one of the exterior sliced holders falling down when they were at about 80%. I was planning to load several weights of slugs and give each a few shots to see how they grouped.and if they would load into my magazine. I never go that far. The holders were not as smooth as I would have liked there were little strings on each of them that I was able to thumbnail off.

I got out to the range today and got the rifle sighted in. I went to refill the rifle and the bleeder valve screw on the compressor was gone. I looked all over the floor of the back seat of the truck and the bag I stored it in. It apears that gremlins decided that they had a use for the screw and took off with it, Im going to have to try to get ahold of the maker and see if they can send me a new one. I am really happy with the RAW I got 4 shots in a hole way smaller than a dime when I finished the sight in process.

Hopefully someone else can test them out sooner than I can get the screw back from the manufacturer of the compressor otherwise I will get right on it when I get the screw.

If anyone knows if it is just a normal thumb screw or if there is something special about the screw that goes on the bleeder valve on one of the 12v compressors please let me know, if I can just run to the hardware store and get another screw that fits rather than wait for a special screw I would love to know. I'm not in the mood to experiment with 4500 psi capable air pressure.



Dan

 

[Triglav]

Aha, I see now. Well, if I'm ever going to get a 3D printer and try printing anything projectiles/pellet related, I'm certainly going to go with PETG; Thank you for laying that information out for me, I appreciate it!

Well, I'm glad that you were able to get such great results with your RAW PCP, a group smaller than a dime is a great achievement! Oh and I'm sorry to hear, that you've lost that valve screw... I hope you're going to be able to get a new one or that you'll find the old one. I've never dealt with air compressors, so I really know anything about them. All I know is, that they're practical and that they pump air into the gun and that's it, haha.

Later...